Bacteria Can "Talk" To Each Other Using Electrical Signals

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Robin Andrews 22 Oct 2015, 13:48

Scientists have discovered that bacteria are able to communicate with each other using electrochemical signals much in the way human nerve cells do. Not only do individual cells transmit electrical signals to each other, but entirely separate colonies of the microbial critters can likely “talk” to each other, coordinating their actions like regiments of soldiers, acting like a cohesive military unit in order to manage resources. The research, led by the University of California in San Diego, was published this week in Nature.

The remarkable discovery came about serendipitously, as many often do. The researchers were examining the growth of bacterial biofilms – large swaths of bacteria – in a laboratory setting, watching as colonies used up nutrients (specifically an amino acid called glutamate) to multiply. When these colonies reached a certain size, however, they stopped growing for a short period of time. These biofilms only then grew again in distinct periods of time, rather than constantly growing as they had previously done so, and the researchers wondered why this might be. 

Suspecting that some form of communication may be involved, they coated the colonies with a fluorescent dye that changes its appearance when an electrical current passes through it. Incredibly, these colonies were using potassium ions – electrically charged particles – to send signals to each other in waves of electricity.

When a bacterial colony grows to a certain size, those in the outer rims have better access to the glutamate in their surrounding environment; the bacteria in the core of the colony begin to starve as they have relatively poor access to the nutrient. An electrical “starvation signal” is then sent by the hungry core bacteria to the peripheries of the colony, which tells them to stop consuming the glutamate, preventing the colony from increasing in size.

During this feasting moratorium, those in the outer region pass nutrients to the core, satiating the hungry organisms. When they’re full and operating at full capacity again, the starvation signal ceases, and the colony’s outer rim bacteria begin consuming glutamate again.

As reported by The Independent, the research team’s lead scientist Dr Gurol Suel said: “Just like the neurons in our brain, we found that bacteria use ion channels to communicate with each other through electrical signals. The community of bacteria within biofilms appears to function much like a ‘microbial brain’.” This electrical signal so far only seems to control the colony’s overall metabolism.

Although all organisms contain this type of electrical channel, and potassium is the dominant ion that is “passed” between cells, electrical signaling is commonly viewed to be the property of neurons, the Nature study notes. The researchers, although focusing on single colonies of bacteria, speculate that multiple colonies of bacteria living in apparent isolation within fluids could communicate effectively using the same mechanism – after all, potassium ions conduct efficiently through watery substances.

It has been known for some time that bacteria communicate using electrochemical signals, and scientists from various institutions hope that they can “hack” this communication and block it. Bacterial antibiotic resistance is increasing by the week, and it is hoped treatments designed to interrupt these signals could reverse this trend.

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